创建一个自定义异常处理程序中间件，根据客户端请求生成响应

Question

如何创建自定义异常处理程序中间件。此中间件应根据调用客户端生成自定义响应。如果客户端通过 AJAX 请求，则响应应该是描述错误的 JSON 响应，否则将客户端重定向到错误页面。

控制器代码

public IActionResult Index()
        {
            return View();
        }

        public IActionResult Privacy()
        {
            return View();
        }

        [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
        public IActionResult Error()
        {
            return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
        }

中间件代码

public class ErrorHandlerMiddleware
    {
        private readonly RequestDelegate _next;

        public ErrorHandlerMiddleware(RequestDelegate next)
        {
            _next = next;
        }

        public async Task Invoke(HttpContext context)
        {
            try
            {
                await _next(context);
            }
            catch (Exception error)
            {
                var response = context.Response;
                var customError = new CustomError();

                switch (error)
                {
                    case AppException e:
                        // custom application error
                        customError.StatusCode = (int)HttpStatusCode.BadRequest; 
                        break;
                    case KeyNotFoundException e:
                        // not found error
                        customError.StatusCode = (int)HttpStatusCode.NotFound;
                        break;
                    default:
                        // unhandled error
                        customError.StatusCode = (int)HttpStatusCode.InternalServerError;
                        break;
                }
                customError.ErrorMessage = error?.Message;

                if (context.Request.ContentType == "application/json;")
                {
                    var result = JsonSerializer.Serialize(customError);
                    await response.WriteAsync(result);
                }
                else
                {
                    context.Response.Redirect("/Errors/CustomError");
                }
            }
        }

自定义错误class代码

public class CustomError
    {
        public int StatusCode { get; set; }
        public string ErrorMessage { get; set; }
    }

错误视图模型

public class ErrorViewModel
    {
        public string RequestId { get; set; }

        public bool ShowRequestId => !string.IsNullOrEmpty(RequestId);
    }

Answer 1

您可以在启动时添加代码 class:

app.UseStatusCodePagesWithReExecute("/errors/{0}");

添加一个控制器（在我的例子中，我用 HttpContext.Request.Headers["Content-Type"] 进行了测试，它应该是 context.Request.ContentType == "application/json;" 对于 MVC项目):

public class ErrorsController : Controller
    {
        [Route("errors/{statusCode}")]
        public IActionResult CustomError(int statusCode)
        {
            if (HttpContext.Request.Headers["Content-Type"] == "application/json")
            {
                
                var cuserr = new CustomError() { ErrorMessage = "err", StatusCode = statusCode };
                return new JsonResult(cuserr);
            }
            else
            {
                if (statusCode == 404)
                {
                    return View("~/Views/Errors/404.cshtml");
                }
                return View("~/Views/Errors/500.cshtml");
            }
            
        }
    }

和观点：

结果：

更多细节，您可以阅读官方文档： https://docs.microsoft.com/en-us/aspnet/core/fundamentals/error-handling?view=aspnetcore-6.0

创建一个自定义异常处理程序中间件，根据客户端请求生成响应

create a Custom Exception Handler Middleware generating response based on client request

model-view-controller

middleware

exception

.net-core

asp.net-core-5.0